The self that summons an image in dreams or imagination has limited sovereignty over it; the conjured tiger arrives stunted, stuffed, or wrong, obeying its own logic rather than the will that called it. Intention and creation are distinct faculties, and the gap between what you mean to make and what appears is itself a fact about the mind.
Identity can be split into the private self who lives and the public persona who authors, with the two related but not identical; the one who experiences things is slowly dispossessed by the one who converts them into pages and gestures. You cannot locate which of the two is writing the account, and that uncertainty is permanent rather than resolvable.
Mirrors are treated as uncanny rather than neutral because they duplicate and extend the number of existing things and faces, making copies that the self never authorized. The horror is not vanity but proliferation: the suspicion that a reflection is a separate inhabited world rather than a passive image.